a) Field of the Invention
The invention relates to an electric reflective plate device and, more particularly, an electric reflective plate device provided to memorize a previous flip angle, to thereby quickly flip the reflective plate to a desired angle to conveniently use the head up display.
b) Description of the Prior Art
The head-up display device is from the aviation technology originally. The head-up display device may directly project messages in front of the cockpit, and pilots may conveniently obtain desired messages without lowering head to check the messages on the instrument board, pilots can easily combine the messages displayed by the head-up display with the outside scene. Since the image reflected into eyes and the central axis of the aircraft is balanced, the height of pilots may not cause error on pitch angles or visual aim. Therefore, the purpose of the head-up display is that pilots may always keep the head-up posture without lowering head to check the messages displayed on the instrument board, to reduce ignoring the rapid change in the external environment during the interval between lowering head and heading-up, and avoid the delay and discomfort due to eyes focal length is adjusted continuously.
It is one of the biggest main reasons of car accidents that drivers' line of sight is away from the front road when driving. In order to reduce the frequency and duration that drivers' line of sight away from the front road, some car manufacturers equip this kind of head-up display inside the luxury cars, thus, the drivers know the information, such as car speed and engine speed, without moving line of sight away from the front windshield, to maintain traffic safety.
In general driving condition, the shortest time of moving the line of sight away from the front road for reading the information displayed on the instrument board is 0.5 second. For the condition of highway speed of 100 km per hour, the car travels 30 meters per second, and the risk is increased when there are a lot of cars on the road. For safety, the car manufacturers may equip the head-up display in some cars to reduce the distraction of drivers, and the head-up display is used as marking practices to attract consumers.
Recently, the technique of the head-up displays used in the cars is less complicated than the head-up displays equipped in aircrafts. It is one kind of optical system, and generally it is consisted of two main equipments, which are a projector and a combiner. The projector is consisted of signal light sources, projection lens and other optical components. The signal light source of the projector is consisted of LCD monitors or CRT equipments. Light is emitted from the signal light source and projected to the combiner on the glass (or a special transparent screen) by the projector, and the combiner displays words or images.
In the recent years, there are many head-up displays for installation in car in the market. These head-up displays may simply display car speed and engine speed, now display water temperature, throttle position, fuel, over-speed warning, reverse image, battery voltage, and even combine the speed radar. Some products are stressed as quick installation, which are just connected to the car PC without using other cables. In the luxury cars of some car manufacturers, the information of the navigation system, front and rear vehicle distance is added into the information displayed by the head-up display, which is increased a lot of convenience for drivers. Besides, the external head-up displays in the market is various, and the prices are from several hundred dollars for simple function ones, to ten thousand dollars for good quality and versatile ones.
As above, a head-up display equipped in car has gradually become a fashion and trend, but mainly, it may improve driving safety. However, installation method of a general reflective screen provided for a head-up display to project is being attached to the front windshield. There is a drawback in this method that a small part of the driving vision may be covered for urgency and convenience in viewing during using navigation, drivers still hope that the driving vision may not be covered during other time. Thus, a folding reflective plate device has been generated. An advantage of this kind of reflective plate device is that the reflective plate may be folded when the head-up display is not being used, so that the driving vision may not be covered, thus, it may be widely loved by drivers.
In the known folding reflective plate device, a shaft mechanism is mainly used as the mechanism for folding the reflective plate, and related techniques may be referred to cited references TW M395992, TW M393139, TW M398743, TW M273183, TW M305555, TW M248211, TW I352165. Strictly speaking, the reflective plate devices adequately use above related techniques, but there is a common drawback that the rotation angle may need to be adjusted every time, it is really inconvenient.